Rhodamine dye solutions

ABSTRACT

Stable concentrated rhodamine dye solutions containing one or more rhodamine dyes esterified with a glycol or glycol derivative. The solutions are particularly suitable for dyeing paper.

United States Patent [191 [in 3,849,065 Schmeidl 14 1 Nov. 19, 1974 [5RHODAMINE DYE SOLUTIONS 3,107,968 10/1963 Pascal 8/55 3,346,322 10/1967Finkenauer et al 8/79 [75 Inventor' g y Frankemhal 3,503,699 3/1970Wellenreuther et a1. 8/93 [73] Assignee: Badische Anilin and Soda-FabrikQTHER PUBLICATIONS Akfiengeseuschaft Ludwigshafen/ Colour Index, 2nded., 1956, Vol. 3, pp. 3384 and Rhein, Germany 3385' [22] Filed: July24, 1972 Primary Examiner-Thomas .1. Herbert, Jr.

. Assistant ExaminerBruce H. Hess [21] Appl 274580 Attorney, Agent, orFirm-Johnston, Root, OKeefe,

Keil, Thompson & Shurtleff [52] 11.8. C1 8/25, 8/7, 260/336 [51] Int.Cl. D06p 1/42, C09b 11/28 [57] ABSTRACT [58] Field of Search 25; 260/336Stable concentrated rhodamine dye solutions containing one or morerhodamine dyes esterified with a gly- [56] References Cted col or glycolderivative. The solutions are particularly UNITED STATES PATENTSsuitable for dyeing paper. 516,584 3/1894 Bernthsen 260/336 2 Claims, N0Drawings RHODAMINE DYE SOLUTIONS The invention relates to stable highlyconcentrated solutions of esterified rhodamine dyes of the formulae (A)and/or (B):

a c an o 2 5 I NHC2H5 1 COOCH2CH2OR (H c N H) 2 2 0 I N (0 141 R1S04coocu cn on in which R is hydrogen, acet yl, propionyl, alkyl of one tofour carbon atoms or a radical of the formula (CH CH O),,R (in which nis the integer 1 or 2);

R is hydrogen, methyl or ethyl; and

R is hydrogen, acetyl, propionyl or alkyl of one to four carbon atoms.

Examples of alkyl radicals R and R are methyl, ethyl, propyl or butyl.

R and R are preferably hydrogen and n is preferably 1.

Diethylene glycol, triethylene glycol and the corresponding monomethyl,monoethyl, monopropyl and monobutyl ethers, glycol acetate and glycolpropionate are compounds of the formula HOCH CH OR. Examples of ethersare ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butylether and diethylene glycol monomethyl ether.

For the prepration of solutions according to the invention, the dye (A)and/or (B) with R being methyl or ethyl may be dissolved or suspended ina compound of the formula Ho-cH CH O-R and the mixture heated to atemperature within the range from about 100 to 200C, preferably from 120to 170C. The methanol; or ethanol liberated by the transesterificationis distilled off, as well as the major portion of any water contained inthe components of the mixture depending on the temperature.

5 col and triethylene glycol.

Preferred methods for the production of solutions ac cording to theinvention consist in alkylating the dye bases of the formulae:

and

(on which the dyes (A) and/0r (B) are based) with dimethyl or diethylsulfate in the polyhydric glycol and/or glycol ether and then effectingtransesterification of the resultant mixture by heating it to the saidtemperatures, or in transesterifying the dye bases with-and in compoundsof the formula HOCH CH OR in the presence of sulfuric acid.

It is apparently sufficient for the production of stable solutions foronly partial transesteriflcation to take place. Advantageous degrees oftransesterification lie within the range from 20 to 70 percent. Nodetails of the reactions which take place are known. The degree sulfuricacid it is advantageous to use 1.01 to about 1.3

moles, preferably from 1.03 to 1.08 moles, of sulfuric acid per mol ofdye base. Esterification temperatures of from to 180C, preferably fromto C, are advantageous; usually the reaction is over after from 65 onehour to six hours. The moist or dry dye base may be used foresterification, and water liberated in the es-- terification or alreadypresent and also readily volatile compounds are distilled off as far aspossible. The degree ofesterification in the solutions may be furtherincreased after esterification equilibrium has been set up, for exampleby adding glycol diacetate in order to bind further water still presentwhich would react with glycol diacetate to form acetic acid and glycolacetate. The presence of small amounts of acetic acid or propionic acidin the solutions according to the invention is favorable.

In addition to the constituents already specified, the solutionsaccording to the invention may contain small amounts, for example up to10 percent, of additional solvents, for example alcohols such asethanol, propanol or butanol; ketones such as acetone or methyl ethylketone; amides such as formamide, dimethylformamide orN-methylpyrrolidone or butyrolactone. Solutions of other basic dyes, forexample from the acridine series or the triphenylmethane series, mayalso be added to the solutions according to the invention for shading.

It is advantageous for the stability of the highly concentratedsolutions according to the invention that they should not contain morethan percent of water; this applies especially to solutions of the dye(A) and mixtures in which dye (A) is present in an amount of more than20 percent based on the total content of dye.

The relative proportions of the components are conveniently chosen sothat the finished solutions contain about 20 to 60 percent of dye basedon the total weight. The amount of dye can be determined by absorbancemeasurement or dyeing and comparing the values obtained with a standard(for example a commercial type of the powdered dye.)

Solutions containing the dyes (A) and (B) in the ratio from 40:60 to60:40 are particularly valuable for industrial paper coloring because ofthe shades which can be achieved with them. Solutions of t he dy es A) ar e 'r'noreover interesting for the production of printing inks.

The following Examples illustrate the invention. The parts andpercentages in the following Examples are by weight unless otherwisestated.

EXAMPLE 1 100 parts of 3,6-bisethylamino-2,7-dimethylfluoran isintroduced into a mixture of 50 parts of diethylene glycol monomethylether and 30 parts of dimethyl sulfate and heated to 100C. After abouthalf an hour 3 parts of dimethyl sulfate is added and after another halfan hour 50 parts of triethylene glycol. The whole is then heated foranother 4 hours at 170C. The vapor passing over is condensed andcollected in a separator. Finally another 75 parts of triethylene glycolis added, the whole is allowed to cool, filtered and a dye solution isthus obtained which remains stable when stored in the cold and in theheat. 235 parts of this solution are equivalent in coloring paper to 100parts of the dye powder Rhodamine F4G (Commercial type, C.l.45,160/methyl ester).

The distillatepassing over is 35 parts; it contains 29 percent ofmethanol. This is equivalent to a transesterification degree of about 60percent.

A similar solution is obtained when the 50 parts of diethylene glycolmonomethyl ether is replaced by 50 parts of ethylene glycol.

EXAMPLE 2 55.5 parts of Rhodamine base B (C.l. 45,170 B) and 44.5 partsof 3,,6-bisethylamino-2,7-dimethy1fluoran LII I are introduced into amixture of parts of diethylene glycol monomethyl ether and 28 parts ofdimethyl sulfate and heated to C. Forty-five minutes later 2.5 parts ofdimethyl sulfate is added followed by another 2.5 parts after anothertwenty minutes. The mixture is kept for half an hour at 90 to C and then90 parts of triethylene glycol is added. The temperature is then raisedto C and kept at this level for 4 hours. The distillate obtainedconsists of 5 parts and contains 84 percent of methanol. This isequivalent to a degree of transesterification of 25 percent.

When heating is carried on for four hours at 143 or 170C, 12 or 16 partsof distillate is obtained having 21 methanol content of 34 percent or42.8 percent corresponding to a degree of transesterification of about25 percent or 41 percent.

The dye solutions thus obtained are somewhat yellower than Rhodamine B(C.l. 45,170) and color paper from an aqueous liquor, the color strengthas compared with powder being 200:100.

EXAMPLE 3 136 parts of moist Rhodamine base B (C.l. 45,170 B) containing36 parts of water is introduced into 90 parts of glycol and whilestirring 26.2 parts of 91.1 percent sulfuric acid is added. The whole isheated gradually to C and the volatile constituents (about 50 parts) aredistilled off. After heating for 4 hours at 150 to C, 15 parts of amixture consisting of 45 percent of glycol diacetate, 40 percent ofglycol monoacetate and 15 percent of glycol is added. The whole is keptat the said temperature for another two hours, allowed to cool andfiltered.

The total weight of the dye solution is brought to 237 parts by addinganother 20 parts of the said mixture of glycol and glycol esters. Thewater content of the solution is 2 percent. Instead of the mixture,other solvents such as acetic acid, propionic acid, dimethylformamide orpyrrolidone may be used.

200 parts of the stable solution thus prepared is equivalent in colorstrength to 100 parts of a compara ble powdered dye (Rhodamine F3B) butthe purity of shade is better and the tone more yellowish.

EXAMPLE 4 90.7 parts of Rhodamine base B (C.l. 45,170 B), containing32.7 parts of water, and 73.8 parts of the moist compound of theformula:

A heating for about four hours at 150 to 155C 27.5

parts of the mixture of glycol and glycol esters specified in Example 3is introduced. The whole is then heated for another two hours, cooledand filtered. The solution thus obtained has a water content of 2.3percent. By

' at 150C 27.5 parts of the mixture of glycol esters spec- 20 adding 20parts of acetic acid and 7 parts of glycol 260 206 panso'r' thissolution is equivalent to 100 parts of parts of a solution is obtainedwhich is stable in storage. Rhodamine F 38 powder (C.l. 45,175) but hasa clearly 145 parts thereof is equivalent in color strength, shade moreyellowish shade and better purity of shade of and purity to 100 parts ofRhodamin l3 powder (C.I. color.

45,170) in the mass coloring of paper. Eth l g1 col ace- 5 tate may alsobe used instead of the mixthre bf glycol EXAMPLE 7 and glycol esters-17.55 parts of moist Rhodamine Base B containing 7.55 parts of water isintroduced into 10 parts of glycol and then 2.25 parts of 93 percentsulfuric acid is added- 5 7 V V l l 10 and the whole is heated to 140C.The volatile constitu- EXAMPLE 5 ents are distilled off in this way..After the mixture has been stirred for about half an hour at 140C,another 0.78 part of 93 percent sulfuric acid is added and stirring iscontinued for another 4 hours at the same temperature. The amount ofdistillate is 8.8 parts. 23.65 parts of solution having a water contentof 5.5 percent 1 is obtained.

200 parts of this solution is equivalent in color strength to 100 partsof the powdered dye Rhodamine F3B; the shade of color is clearly moreyellow and the purity is better.

A similar solution is obtained by using 9 parts of glycol and 261 partsofa 91 percent sulfuric acid and raising the temperature to 155C. 19.93parts ofa dye solu- 176.6 parts of the moist compound having the formulaindicated in Example 4 and containing 76.6 parts of water is introducedwith stirring into 150 parts of glycol and then 27.4 parts of 91.1percent sulfuric acid is introduced. The temperature is then raised to150C while stirring and the volatile constituents (in all about 100parts) are distilled off. After heating for four hours ified in Example3 is added and the whole is heated for I another two hours at 150C andthen cooled. 281 parts of a dye solution having a water content of 7.4parts and a content of free sulfuric acid of 1.5 parts is obtaihedtionis thus obtained of which 200 parts after dilution 29 Parts of a Solventfor example y acetic acid with 3.67 parts of acetic acid, propionic acidor butanol formic acid, P py carbonate hutymlactohei ethyl is equivalentin color strength to 100 parts of powdered glycol or the mixture ofglycol and glycol esters speci- Rhodamine F33,

fied in Example 3 is added. 310 parts of a dye solution is obtained. 290parts of this solution is equivalent to 30 EXAMPLE 8 100 parts of acomparable Powdered Product 8.8 parts of moist Rhodamine Base B,containing 5.8

when 15 Parts of Euchrysih GGNX Base parts of dry base, and 7.25 partsof the moist compound 46,040 Base) and Parts of the mixture of glycol ofthe formula indicated in Example 4 are introduced and gly o sters spified .in Ex mp 3 a d d to into l0 parts of glycol, 2.63 parts of9l.lpercent sulfuthe 281 parts of y solution obtained above, 300 parts ricacid is added and the whole is heated for 5 hoursat of the solution thusobtained is equivalent to 100 parts 150C 8,5 part5 thus distill off and20.2 parts of a con- Of Rhodamine 6 GDN extra Poll/ller with the Same Pcentrated dye solution remains which is diluted with y of shade and asomewhat more yellowish 5.8 parts of acetic acid or a mixture of glycoland acetic The content of free sulfuric acid may be lowered for id i thti 1:1, example y adding Rhodamine 6G methyl ester bicar- 40 150 partsof the solution obtained is equivalent in the bohate (3s6'bisethylamhloy mass coloring of paper to 100 parts of powderedRhocarbbmelhoxyphenyll-xanthylium bicarbonate) or y damine FB (Cl. .170)in color strength with the ammonium carbonate. seine purity of shade anda somewhat yellower tone.

When the reaction is carried out at 170C instead of I claim: at 150C, alarger amount of distillate and a daye hav- 45 1. A stable highlyconcentrated solution of an esteriing a more bluish shade is obtained.fied rhodamine dye of the formula (A) EXAMPLE 6 in which R is hydrogen,acetyl, propionyl, alkyl of one to four 10 parts of Rhodamine base B isintroduced into 13 carbon atoms or a radical of the formula parts ofglycol and while stirring 2.6 parts of 91.1 per- (Cl-l CH O),,R centsulfuric acid is added. The temperature is then n is the integer 1 or 2;raised to 140C and maintained for five hours. The vol- R is hydrogen,methyl or ethyl; and atile constituents are distilled off. The whole isallowed R is hydrogen, acetyl, propionyl or alkyl of one to to cool,filtered and 24.4 parts of a stable solution is obfour carbon atoms.

tained. It contains 0.76 part of water and 0.3 part of 2. A stablehighly concentrated solution of esterified free sulfuric acid. vrhodamine dyes of the formulae (A) and (B) sou(") in which R is hydrogenmethyl or ethyl; and

R is hydrogen, acetyl, propionyl, alkyl of one to four R is hydrogen,acetyl, propionyl or alkyl of one to carbon atoms or a radical of theformula four carbon atoms, wherein the ratio of dyes (A) -Z HZ ),.R and(B) is from 40:60 and 60:40. ,!1.ilh i tg 3x2; a

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. I 3,849,065

DATED November 19, 1974 INVENTOR(S) SCHMEIDL It is certified thaterrarappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

In the Heading, insert [30] Foreign Application Priority Data July 30,1971 Germany P 21 38 178.2 and June 9, 1972 Germany P 22 28 260.6

Signed and Sealed this Twenty-seventh Day Of July 1976 [SEAL] Arrest.-

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufParenrsand Trademarks

1. A STABLE HIGHLY CONCENTRATION SOLUTION OF AN ESTERIFIED RHODAMINE DYEOF THE FORMULA (A) 2,7-DI(CH3-),3-(C2H5-N(+)=),6-(C2H5-NH-),9-(2-(R-O-CH2-CH2-OOC-)PHENYL)-3H-XANTHENE . R1-SO4(-) IN WHICH R ISHYDROGEN, ACETYL, PROPIONLY, ALKYL OF ONE TO FOUR CARBON ATOMS OR ARADICAL OF THE FORMULA (CH2CH2O)NR2; N IS THE INTEGER 1 OR 2; R1 ISHYDROGEN, METHYL OR ETHYL; AND R2 IS HYDROGEN, ACETYL, PROPIONYL ORALKYL OF ONE TO FOUR CARBON ATOMS,
 2. A stable highly concentratedsolution of esterified rhodamine dyes of the formulae (A) and (B)